Wilke, U.S. Pat. No. 4,693,272, discloses a basic reciprocal spool control valve for use in controlling hydraulic cylinders on various types of mobile hydraulic equipment. This type of valve can take the form of a sectional valve, several of which may be used together. Such valves are used to control multiple functions, such as raising and lowering mechanical members, tilting or rotating the members around other axes of motion, and sliding members fore and aft.
Prior to the invention herein, there was an operational problem in the art in that the operator of such equipment had to simultaneously manage two separate controls on the machine to achieve optimum cylinder actuation. When the spool actuating lever Was operated to provide hydraulic fluid to a cylinder, an increase in the rotational velocity of the prime mover was also needed to produce the required hydraulic pressure and flow. It has therefore been desirable to find some improved method for simultaneous of control of these functions.
Additional valves with linkages could be added to the prior hydraulic function control valve to control the speed of the prime mover.
This would be disadvantageous in adding to the space previously occupied by a control valve of the prior art. It would also add to the mechanical complexity of the system, in order to support additional functions.